System and Method for Monitoring Scale Removal from a Wellbore

ABSTRACT

A technique enables the cleaning of scale from a well and the monitoring of scale removal. A scale removal tool and a radiation detector are deployed simultaneously into a wellbore having scale with a radioactive signature. The scale removal tool is used to remove deposits from a well component, e.g. from the interior of a tubular member. The radiation detector enables the measuring and monitoring of scale removal. Data related to the scale removal can be output for use by an operator to help optimize scale removal and fluid flow.

BACKGROUND

In many well environments and applications, the development of scale can be problematic for downhole completion equipment and other downhole components. Scale can result from a variety of deposits that form along the interior of tubulars, e.g. production tubing or casing, or on other well related equipment. Scale often is formed in oil or gas wells that produce water or as result of water injection to enhance recovery. If left untreated, the scale can inhibit or prevent fluid flow along the wellbore.

Several techniques have been used in the removal of scale from tubing and other well equipment. For example, some types of scale can be dissolved by a pumping specific treatment fluids downhole. In other applications, scale is removed by directing a jet of abrasive slurry against the scale to effectively chip away at the scale deposits. In any of these approaches, difficulty arises in determining the extent of the scale removal and thus the success of the treatment.

SUMMARY

In general, the present invention provides a system and method for cleaning scale from a well and for monitoring removal of the scale. A scale removal tool and a radiation detector are deployed simultaneously into a wellbore having scale with a radioactive nature. The scale removal tool is operated to remove scale from a well component, e.g. from the interior of a tubular member. The radiation detector is utilized in locating scale deposits, measuring the extent of the scale removal, and outputting data related to the extent of scale removal.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:

FIG. 1 is a front elevation view of a well system deployed into a wellbore for scale removal, according to an embodiment of the present invention;

FIG. 2 is a schematic representation of a scale removal bottom hole assembly deployed via a coiled tubing conveyance system, according to an embodiment of the present invention;

FIG. 3 is a front elevation view of the bottom hole assembly illustrated in FIG. 2, according to an embodiment of the present invention;

FIG. 4 is a cut away view of a coiled tubing conveyance with a communication line, according to an embodiment of the present invention; and

FIG. 5 illustrates one example of a display for providing information to an operator regarding scale removal, according to an embodiment of the present invention.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

The present invention relates to a system and methodology for determining the location of scale deposits and for monitoring removal of the scale. The system and methodology enable the accurate monitoring of scale removal through detection of the radioactive nature of the scale. For example, barium sulfate has a radioactive nature/signature that is detected and monitored to determine the amount of scale remaining in a well component. A radiation detector, such as a gamma ray detector, is used to detect the radiation and output data to a surface acquisition unit indicative of the amount of remaining scale.

In one example, data from the gamma ray detector is provided along with a casing collar locator log to determine the presence and location of barium sulfate scale. Gamma ray readings indicate the presence of barium sulfate scale, and higher readings indicate greater buildup of scale. A surface readout may be used to provide operational information related to the cleanout procedure, and may include a variety of parameters such as string weight, speed, pump rate, and pressure. These parameters inform an operator as to whether further cleanout progress remains feasible.

The system also can be designed to provide downhole data to the surface in real time. By way of example, data from the radiation detector and other downhole sensors can be transmitted uphole via a communication line, such as a fiber optic line. Both data from the radiation detector and data from other downhole sensors, e.g. pressure sensors, temperature sensors, casing collar locator detectors, can be sent uphole to a surface acquisition unit to enable monitoring and/or optimization of the scale removal.

Removal of scale can be accomplished by pumping appropriate scale removal materials downhole. If the cleanout equipment is conveyed downhole by coiled tubing, fluid based scale removal materials can be pumped down through the coiled tubing. In one example, scale removal material is pumped under pressure through a jetting tool used to direct high-pressure fluid through one or more jetting nozzles and against the scale buildup. The scale removal material may comprise combinations of liquid and particulate matter able to remove scale buildup when directed against the scale under pressure. For example, scale removal materials are available from Schlumberger Corporation, of Houston, Tex., and include materials containing sterling beads and cleanout gels or fluids designed to enhance the removal of scale. As the scale is removed, the radiation detector, e.g. gamma ray detector, is used to monitor the removal process.

Referring generally to FIG. 1, one example of a well system 20 is illustrated according to an embodiment of the present invention. In this example, well system 20 comprises a bottom hole assembly 22 that may have a variety of components related to a well cleanout procedure. For example, bottom hole assembly 22 may comprise a radiation detector 24, e.g. a gamma ray detector, and a scale removal tool 26, such as a jetting tool. The bottom hole assembly 22 is moved downhole to a desired cleanout area 28 that may have deposits 30 resulting from scale buildup. Commonly, the deposits 30 are caused by barium sulfate or other scale forming materials having a radioactive nature/signature.

In the example illustrated, the scale buildup 30 is formed within a tubular member 32 through which bottom hole assembly 22 is run downhole. However, bottom hole assembly 22 can be utilized in the removal of scale deposits from other downhole components. The tubular member 32 may comprise casing, production tubing, completion tubing, or other tubular members deployed in a wellbore 34. As illustrated, wellbore 34 is lined with a wellbore casing 36, and desired regions can be isolated along tubular member 32 by locating one or more packers 36 between tubular member 32 and wellbore casing 36.

As illustrated in FIG. 1, wellbore 34 extends down from surface equipment 38 positioned at a surface location 40. Surface equipment 38 may comprise a rig for deploying bottom hole assembly 22 on a conveyance 42. By way of example, conveyance 42 comprises tubing, such as coiled tubing. A surface acquisition unit 44 is positioned at surface location 40 and communicates with bottom hole assembly 22 and its various sensors/detectors via one or more communication lines 46. Communication lines 46 may comprise one or more hardwired lines routed along conveyance 42 or, in some applications, may comprise wireless communication lines.

The bottom hole assembly 22 is moved downhole to enable radiation detector 24 to detect the presence of scale deposits 30. Once detected, scale removal tool 26 is used to remove the scale buildup, and radiation detector 24 is used to monitor the removal. In the embodiment illustrated, scale removal tool 26 comprises a jetting tool, and radiation detector 24 comprises a gamma ray detector. A scale removal material is flowed under pressure downhole, e.g. through coiled tubing conveyance 42, as represented by arrows 48. The scale removal material is flowed through gamma ray detector 24 to jetting tool 26. Jetting tool 26 directs the pressurized scale removal material outwardly through one or more jets 50 against scale deposits 30.

In embodiments that utilize a coiled tubing conveyance 42, the bottom hole assembly 22 is conveyed downhole by a coiled tubing injection system 52, as illustrated in FIG. 2. In this example, coiled tubing injection system 52 comprises a coiled tubing reel 54 from which a coiled tubing conveyance 42 can be unspooled to convey bottom hole assembly 22 downhole or spooled to withdraw the coiled tubing conveyance and bottom hole assembly 22. The coiled tubing reel 54 deploys coiled tubing through a coiled tubing injector 56 which orients and delivers the coiled tubing downhole into wellbore 34. Preferably, movement of the coiled tubing reel 54 and coiled tubing conveyance 42 is controlled by a suitable surface control unit 67 coupled to a suitable power source. Alternatively, movement of the coiled tubing reel 54 and coiled tubing conveyance 42 can be controlled by a suitable surface control unit 58 coupled to a power source 60 and a pressure bulkhead 62.

Additionally, the communication line or communication lines 46 can be deployed downhole with conveyance 42. For example, communication line 46 can be mounted on the coiled tubing or deployed within the coiled tubing. The communication line 46 is connected to surface acquisition unit 44 to receive data sent uphole from bottom hole assembly 22. In the example illustrated, surface acquisition unit 44 may comprise a computer based control having a computer 64 with a suitable processor or processors programmed to process data received from components of bottom hole assembly 22. Computer 64 also can be used to process data received from a variety of other sensors/components of well system 20. Information on scale removal, pressure, temperature, casing collar locations, and other data can be displayed on one or more displays 66 located at the well site or at other locations. In this example, each display 66 uses a suitable graphical user interface to provide scale removal information and other desired information in a format useful to an operator. In some applications, computer 64 also can be used to output data downhole to control various downhole components.

Referring generally to FIG. 3, one embodiment of bottom hole assembly 22 is illustrated. The bottom hole assembly 22 comprises a variety of components that are used in removing scale and monitoring the scale removal. The bottom hole assembly components help optimize both scale removal and the subsequent fluid flow through the member from which scale deposits are removed. The number, type and arrangement of components can vary from one application to another, however FIG. 3 illustrates an arrangement suitable for many types of applications.

As illustrated, the scale removal tool 26 is a jetting tool located at a lower position of bottom hole assembly 22. The jetting tool 26 directs and discharges scale removal material through jetting nozzle 50, as represented by arrows 68. A filter 70 is positioned to filter the scale removal material before it enters jetting tool 26. Filter 70 is designed to remove debris that can potentially clog or damage jetting tool 26. A check valve section 72, having check valves 74, provides a well control pressure barrier. Check valve section 72 may be located adjacent filter 70 on a side opposite jetting tool 26.

The illustrated bottom hole assembly 22 also comprises a variety of sensors to detect and monitor a variety of downhole parameters. For example, radiation detector 24, e.g. a gamma ray detector, is positioned to detect radiation from the scale deposits. The radiation detector 24 comprises a flow passage 76 through which scale removal material is flowed to jetting tool 26. Other sensory devices may comprise a casing collar locator 78 and a stress detector 80 for detecting tension and compression in bottom hole assembly 22. As illustrated, casing collar locator 78 and stress detector 80 are positioned between radiation detector 24 and check valve section 72. Additionally, a monitoring section 82 may comprise one or more pressure sensors 84 and temperature sensors 86. In many applications, pressure sensors 84 are positioned to measure internal pressures within bottom hole assembly 22 and external pressures outside bottom hole assembly 22.

Data from the radiation detector 24 and other sensors, as well as control signals sent downhole from surface acquisition unit 44, are handled by an electronics section 88 that may be positioned above radiation detector 24 and monitoring section 82. Electronics section 88 is designed according to the surface acquisition system utilized. By way of example, electronics section 88 may comprise a bulkhead for terminating an optical fiber communication line, a power section to provide downhole power storage, and a suitable telemetry control for sending and receiving data. A connector 90 is used to connect bottom hole assembly 22 to coiled tubing conveyance 42 or to another type of conveyance.

The use of coiled tubing for conveying bottom hole assembly 22 downhole creates an internal flow path along which the scale removal material can be flowed downhole, while also providing a structural feature along which the communication lines 46 can be routed. As illustrated in FIG. 4, for example, conveyance 42 comprises coiled tubing 92 having an interior 94 that creates a passage along which the scale removal material flows downhole. In this example, communication line 46 is routed along interior 94 of coiled tubing 92. However, communication line 46 also can be attached to an exterior of the coiled tubing 92, or it can be deployed within the wall forming coiled tubing 92. By way of example, communication line 46 comprises a small protective tube 96 that surrounds one or more optical fibers 98. The optical fibers 98 enable telemetry between surface acquisition unit 44 and bottom hole assembly 22. Data can be carried by optical fibers 98 both to and from the surface acquisition unit 44.

During a scale removal operation, data from the various sensors in bottom hole assembly 22 is provided to surface acquisition unit 44, processed as necessary to a desired form, and output to display device 66. For example, data from gamma ray detector 24 can be output to the one or more display devices 66 in a form that helps an operator identify and visualize scale build up in tubular member 32. During scale removal, the gamma ray detector 24 can be continually operated to provide updated data to surface acquisition unit 44. This allows an operator to monitor the scale removal progress. A variety of other data, including temperature data, pressure data, casing collar data and other information also can be provided to surface acquisition unit 44 and displayed for use and evaluation by an operator. Furthermore, the data can be processed by computer 64 according to a variety of models or algorithms to present additional information to an operator related to scale removal and other aspects of the well.

FIG. 5 provides one example of a graphical user interface 100 that can be used to display information to an operator via display 66. In this particular example, graphical user interface 100 displays information related to scale deposits 30 in tubular member 32. By way of example, the graphical user interface 100 provides a graphical representation of the well 102 with features illustrated in a manner helpful to an operator. The graphical representation 102 illustrates the scale deposits 30 at a particular depth based on information provided by gamma ray detector 24. In addition or as an alternative, a graphical representation 104 can be used to illustrate a gamma ray detector log having data indicative of scale deposits at specific depths. Of course, the data related to scale deposits can be illustrated or presented in a variety of other formats. Additionally, the displays 66 can be used to provide the operator with other types of information based on data from many types of sensors in bottom hole assembly 22. As described previously, various software models and algorithms can be run on computer 64 to process data obtained from the downhole environment to provide additional well analysis, including scale removal analysis. The resulting analysis is displayed via graphical user interface 100 in a desired format.

As the scale removal operation progresses, the gamma ray detector 24 is used to periodically or continuously measure the radioactive nature of the scale deposit. The resulting data is transmitted uphole to provide an operator with information on the extent of the remaining scale deposit. In many applications, the data can be transferred uphole in real time to keep an operator updated throughout the scale removal operation. The real time monitoring is particularly helpful in optimization of the scale removal procedure. The surface acquisition unit 44 records and displays the downhole information, allowing the operator to adjust the depth of the bottom hole assembly and to compare real time readings against an existing baseline well log to enable real time optimization of the procedure.

The present system and methodology enable monitoring of scale removal operations through detection of scale deposits based on the radiation signature of the deposits. By using a gamma ray detector, for example, the position and amount of barium sulfate scale or other radioactive scale can be determined by the strength of the radioactive signature. Also, the ability to output data to surface acquisition unit 44 in real time facilitates immediate optimization of the scale removal procedure. The scale removal is further optimized by virtue of the internal flow passage extending through the radiation detector and other bottom hole assembly components to enable pumping of a variety of treatment fluids down through a coiled tubing conveyance and through the bottom hole assembly components to the scale removal tool 26. As a result of the design and monitoring ability, both the scale removal material, e.g. treatment fluid, and the jetting tool can be selected and subsequently adjusted to optimize scale removal. In some applications, the ability to use coiled tubing as the conveyance enables and improves the functionality of a variety of communication lines, such as fiber optic lines.

Accordingly, although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Such modifications are intended to be included within the scope of this invention as defined in the claims. 

1. A method of performing a well cleanout, comprising: simultaneously deploying a jetting tool and a gamma ray detector downhole into a wellbore on coiled tubing; locating scale at a wellbore location with the gamma ray detector; pumping a cleanout material down through the coiled tubing and out through the jetting tool to remove scale at a the wellbore location; and monitoring the removal of scale with the gamma ray detector.
 2. The method as recited in claim 1, wherein monitoring comprises monitoring in real time.
 3. The method as recited in claim 1, wherein pumping comprises pumping the cleanout material through the gamma ray detector.
 4. The method as recited in claim 1, further comprising outputting data from the gamma ray detector to a surface acquisition unit.
 5. The method as recited in claim 4, wherein outputting comprises outputting the data along a communication line routed along an interior of the coiled tubing.
 6. The method as recited in claim 4, wherein outputting comprises outputting the data along a fiber optic line routed along an interior of the coiled tubing.
 7. The method as recited in claim 6, further comprising measuring temperature and pressure proximate the gamma ray detector; and outputting temperature and pressure data to the surface acquisition unit.
 8. The method as recited in claim 4, wherein locating further comprises measuring casing collar locations; and outputting casing collar location data to the surface acquisition unit.
 9. A system for use in a wellbore, comprising: a bottom hole assembly having: a jetting tool comprising at least one jetting nozzle oriented to direct a scale removal material against a well component surface; a radiation detector positioned to detect and locate scale buildup along the well component surface.
 10. The system as recited in claim 9, wherein the radiation detector comprises a gamma ray detector positioned to detect scale buildup within a tubular.
 11. The system as recited in claim 10, wherein the gamma ray detector comprises a passage through which the scale removal material passes as it flows to the jetting tool.
 12. The system as recited in claim 9, further comprising a coiled tubing string coupled to the bottom hole assembly to convey the bottom hole assembly downhole.
 13. The system as recited in claim 12, further comprising a surface acquisition unit and a communication line connecting the radiation detector with the surface acquisition unit.
 14. The system as recited in claim 13, wherein the communication line comprises a fiber optic line deployed within the coiled tubing string.
 15. A method, comprising: determining a location of a scale deposit within an interior of a tubular positioned in a wellbore; removing scale from an the interior of the tubular positioned in a wellbore; monitoring scale removal with a radiation detector; providing data on the scale removal in real time to a surface acquisition unit and determining the extent of the remaining scale deposit.
 16. The method as recited in claim 15, wherein monitoring comprises monitoring scale removal with a gamma ray detector.
 17. The method as recited in claim 15, wherein monitoring comprises detecting the radioactive signature of barium sulfate.
 18. The method as recited in claim 15, wherein removing comprises directing a jet of fluid and beads against the scale.
 19. The method as recited in claim 18, wherein directing comprises directing sterling beads against the scale.
 20. The method as recited in claim 15, wherein providing comprises providing data through a communication line routed along a coiled tubing string.
 21. The method as recited in claim 15, wherein providing comprises providing data through a fiber optic line routed along an interior of a coiled tubing string.
 22. A system, comprising: a surface acquisition unit; a coiled tubing string; a communication line routed along the coiled tubing string to communicate data to the surface acquisition unit; and a bottom hole assembly coupled to the coiled tubing string and the communication line, the bottom hole assembly comprising: a jetting tool oriented for scale removal; and a gamma ray detector to determine a location of scale and to monitor the extent of scale removal.
 23. The system as recited in claim 22, wherein the communication line is routed along an interior of the coiled tubing string.
 24. The system as recited in claim 22, wherein the bottom hole assembly further comprises a monitoring section having temperature and pressure sensors.
 25. The system as recited in claim 22, wherein the gamma ray detector comprises a flow passage to enable flow from the coiled tubing, through the gamma ray detector, and to the jetting tool. 